ES2522573T3 - Controlled release fertilizer and method for its production - Google Patents

Abstract

A controlled release fertilizer material comprising a particulate plant nutrient surrounded by a coating, which is the reaction product of a mixture comprising: a polyol consisting of castor oil, an isocyanate and an organic wax, characterized in that : (i) the organic wax comprises a C20 + alpha olefin, and (ii) the coating is present in an amount in the range of about 1 to 4 percent by weight, based on the weight of the particulate plant nutrient, and the amount of organic wax in the mixture is in the range of 1 to 25 percent by weight, based on the combined weight of the organic wax and the polyol.

Description

image 1

DESCRIPTION

Controlled release fertilizer and method for its production

5 Technical field

The present invention relates to a controlled release fertilizer and method for its production.

Background of the prior art

10 Fertilizers have been used for many years to supplement nutrients to a growing environment.

In recent years the technique has focused on methods to deliver controlled amounts of nutrients for plants to the soil or other growth medium. This has been carried out, so that, on the one hand, the plants

15 in growth do not be adversely deprived of nutrients, and on the other hand, an excess supply of nutrients is avoided. An excess supply of nutrients can cause toxicity in plants or losses due to leaching. The resulting improvement in the effectiveness of fertilizer use (FUE) can reduce the speed and frequency of nutrient application.

The Canadian patent application 2,272,480 describes a controlled release fertilizer material, which comprises a granulated coated fertilizer coated with a thermosetting resin. The dissolution rate of the fertilizer is delayed by containing a hydrophobic compound in at least one coating portion and one fertilizer portion. This document does not mention the use of castor oil in the thermosetting resin, nor any effect resulting from its application.

25 U.S. Patent 5,538,531 [from Hudson et al. (Hudson)] and the prior art cited therein, provides a useful overview of methods for providing controlled release properties to a particulate plant nutrient. Specifically, Hudson teaches a controlled release particulate fertilizer product, which has a central mass of water-soluble fertilizer incorporated into a plurality of coatings resistant to

30 water insoluble abrasion. At least one internal coating is a product of the urethane reaction derived from the isocyanates and polyols mentioned. The outer coating is formed from an organic wax having a drip point in the range of 50 ° C to 120 ° C. The general teachings and those of the examples in the Hudson patent make it clear that the Hudson process involves curing the urethane coating (s) surrounding the particulate plant nutrient, and then applying the outer layer of organic wax to or from the

35 cured urethane coatings.

It is also known in the art to previously coat a particulate plant nutrient with an organic wax or similar material, as a means to regularize or somehow improve, the surface of the particulate plant nutrient before coating it with urethane-forming reagents.

40 Despite these advantages of the technique, there is still room for improvement. Specifically, it would be desirable to obtain a controlled release fertilizer and a process for the production thereof, which would allow the easy adaptation of the release rate profile of a particular nutrient for particulate plants, to which a certain amount of coating or coatings is applied. urethane Also, it would be desirable to be able to achieve

A desired release rate profile for a particular nutrient for particulate plants, using significantly reduced amounts of coating materials.

Description of the invention

It is an object of the present invention to provide a new controlled release fertilizer, which avoids or mitigates at least one of the aforementioned disadvantages of the prior art.

Consequently, in one of its aspects, the present invention provides a controlled release fertilizer material, comprising a particulate plant nutrient surrounded by a coating that is the product of

The reaction of a mixture, comprising:

a) A polyol consisting of castor oil, an isocyanate and an organic wax, characterized in that:

60 (i) the organic wax comprises a C20 + alpha olefin, and

(ii) the coating is present in an amount in the range of about 1 to 4 percent by weight, based on the weight of the particulate plant nutrient, and the amount of organic wax in the mixture is in the range of 1 to 25 weight percent, based on the combined weight of organic wax and polyol.

In another of its aspects, the present invention provides a process for producing a controlled release fertilizer material, comprising the steps of:

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a) contacting a particulate plant nutrient with a mixture comprising: a polyol consisting of castor oil, an isocyanate and an organic wax to produce a coating around the particulate plant nutrient, and b) curing the coating to produce the controlled release fertilizer material, characterized in that:

(i)

the organic wax comprises a C20 + alpha olefin, and

(ii)

The coating is present in an amount in the range of about 1 to 4 percent by weight, based on the weight of the particulate plant nutrient, and the amount of organic wax in the mixture is in the range of 1 to 25 percent in weight, based on the combined weight of organic wax and polyol.

Therefore, the authors of the present invention have surprisingly and unexpectedly found that a controlled release fertilizer material and process for the production thereof can be obtained from a coating that is the product of the reaction of a mixture comprising: castor oil, an isocyanate and an organic wax comprising a C20 + alpha olefin. Specifically, although the use of wax as a coating prior to the application of the urethane layer and / or as a coating after the application of the urethane layer is known, the advantages of incorporating the wax with the urethane forming reagents so far have been They don't know These advantages include:

(i) the ability to extend the release rate profile for a given nutrient for 25 plants, which has a certain amount of urethane coating on it;

(ii) the ability to achieve a desired release rate, using significantly less coating than used in comparable prior art coating methods; Y

(iii) the ability to obtain said product through a one-stage procedure (ie, compared to the multi-stage procedures of the prior art).

Other advantages will be apparent to those skilled in the art from the present specification.

As described above, the present controlled release fertilizer material comprises a coating derived from a mixture comprising: a polyol consisting of castor oil, an isocyanate and an organic wax comprising a C20 + alpha olefin. The polyol and isocyanate react chemically and form a urethane. It is believed that the organic wax physically intermingles with the urethane thus formed, that is, it is believed that the organic wax used herein is chemically substantially inert to the polyol and isocyanate components. The resulting coating is a substantially homogeneous layer. In other words, unlike the prior art approach described by Hudson or others involving multiple coatings other than urethane and wax, the coating produced in the controlled release fertilizer of the present invention incorporates urethane and organic wax in at least one substantially homogeneous layer (naturally, multiple such coatings are contemplated within the scope of the controlled release fertilizer material). In this context, it should be understood that the term "homogeneous" is used in a somewhat broad sense, in order to exclude a controlled release fertilizer material comprising only different layers of urethane and wax (for example, the material

45 fertilizer described by Hudson).

As used throughout this specification, the term "urethane-containing compound" means a product obtained by reacting a polyol and an isocyanate. Typically, the compound so produced will be a polyurethane.

Brief description of the figures

Embodiments of the present invention will be described with reference to the attached figure, which illustrates the release rate profile of a controlled release fertilizer according to the present invention and the release rate profiles of controlled release fertilizers of the present invention. prior art

Best way to carry out the invention

Accordingly, in one of its aspects, the present invention relates to a controlled release fertilizer material comprising a particulate plant nutrient surrounded by a coating.

The choice of the particulate plant nutrient material useful for the controlled release fertilizer material of the present invention is not particularly restricted and falls within the scope of the person skilled in the art.

65 For example, the plant nutrient material used can be selected from those described by Hudson. Preferably, said plant nutrient comprises a water-soluble compound, more preferably a compound containing at least one member selected from the group consisting of nitrogen, phosphorus, potassium, sulfur and mixtures thereof. A preferred plant nutrient comprises urea. Other useful examples of plant nutrients are described in US Pat. 5,571,303 (Bexton), for example, ammonium sulfate, ammonium phosphate and mixtures thereof.

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5 The coating surrounds the plant nutrient material in an amount in the range of about 1.0 to 4 percent by weight, preferably about 2.0 to 4.0 percent by weight, based on the weight of the nutrient material for plants.

The coating is the reaction product of a mixture comprising a polyol consisting of castor oil, an isocyanate and an organic wax comprising a C20 + alpha olefin.

The isocyanate suitable for use in producing the coating is not particularly restricted and the choice thereof is within the scope of the person skilled in the art. In general, the isocyanate compound suitable for

15 use can be represented by the general formula:

Q (NCO) i

where i is an integer of two or more and Q is an organic radical that has the valence of i. Q may be a substituted or unsubstituted hydrocarbon group (for example, alkylene or arylene group). Also, Q can be represented by the general formula:

Q1-Z-Q1

Wherein Q1 is an alkylene or arylene group and Z is selected from the group comprising -O-, -O-Q1-, -CO-, -S-, -SQ1-S-and -SO2-. Examples of isocyanate compounds that fall within the scope of this definition include hexamethylene diisocyanate, 1,8-diisocyanate-p-methane, silyl diisocyanate, (OCNCH2CH2CH2OCH2O) 2, 1-methyl2,4-diisocyanoccyclohexane, phenylene diisocyanates, diisocyanates of tolylene, chlorophenylene diisocyanates, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane-4,4 ', 4 "-triisocyanate and isopropylbenzene-alpha-4-diisocyanate.

In another embodiment, Q may also represent a polyurethane radical with a valence of i. In this case Q (NCO) i is a compound commonly known in the art as a prepolymer. In general, a prepolymer can be prepared by reacting a stoichiometric excess of an isocyanate compound (discussed above.

35 herein) with an active hydrogen containing compound (discussed hereinbefore), preferably polyhydroxyl-containing materials or polyols described above. In this embodiment, the polyisocyanate can be used, for example, in proportions of about 30 percent to about 200 percent stoichiometric excess with respect to the proportion of hydroxyl in the polyol.

In another embodiment, the isocyanate compound suitable for use in the process of the present invention can also be selected from dimers and trimers of isocyanates and diisocyanates, and from polymeric diisocyanates with the general formula:

[Q "(NCO) i] j

Wherein both i and j are integers that have a value of 2 or more, and Q "is a polyfunctional organic radical, and / or, as additional components in the reaction mixture, compounds with the general formula:

L (NCO) i

where i is an integer that has a value of 1 or more and L is a monofunctional or polyfunctional radical or atom. Examples of isocyanate compounds that fall within the scope of this definition include ethyl phosphonic diisocyanate, phenylphosphonic diisocyanate, compounds containing a group = Si-NCO, sulfonamide-derived isocyanate compounds (QSO2NCO), cyanic acid and thiocyanic acid.

55 See also, for example, British Patent No. 1,453,258.

Non-limiting examples of suitable isocyanates include: 1,6-hexamethylene diisocyanate, 1,4butylene diisocyanate, furfurylidene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,4'diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenylpropane diisocyanate, 4,4'-diphenyl-3,3'-dimethyl methane diisocyanate, 1,5-naphthalene diisocyanate, 1-methyl-2,4- diisocyanate-5-chlorobenzene, 2,4-diisocyanate-s-triazine, 1-methyl-2,4-diisocyanate cyclohexane, p-phenylene diisocyanate, m-phenylene diisocyanate, 1,4naphthalene diisocyanate, dianisidine diisocyanate diisocyanate , 1,4-silylene diisocyanate, 1,3-silylene diisocyanate, bis- (4-isocyanophenyl) methane, bis- (3-methyl-4-isocyanophenyl) methane, polyphenyl polymethylene polyisocyanates and mixtures thereof.

Particularly preferred isocyanate groups are those described in Hudson.

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Preferably, castor oil and isocyanate are used in amounts so that the ratio of NCO groups in the isocyanate to hydroxyl groups in castor oil is in the range of about 0.8 to about 3.0, more preferably of about 0.8 to about 2.0, the most

5 preferably from about 0.9 to about 1.1.

The wax comprises a C20 + alpha olefin, more preferably a C20-40 alpha olefin.

The organic wax is present in the mixture in an amount in the range of about 1.0 to about 25 percent by weight, based on the combined weight of the organic wax and the polyol. Most preferably, the organic wax is present in the mixture in an amount in the range of about 2.0 to about 10 percent by weight, based on the combined weight of the organic wax and the polyol.

Step (a) in the process herein comprises contacting a plant nutrient

Particulate with a mixture comprising: a polyol consisting of castor oil, an isocyanate and an organic wax comprising a C20 + alpha olefin to produce a coating around the particulate plant nutrient. The precise way of applying the mixture to the plant nutrient is not particularly restricted (see, for example, column 5, lines 31-63 in Hudson).

In the process herein, it is preferred to carry out Step (a) at a temperature in the range of about 50 ° C to about 105 ° C, more preferably in the range of about 60 ° C to about 90 ° C, most preferably in the range from about 70 ° C to about 80 ° C.

Preferably, Step (a) comprises contacting the particulate plant nutrient with a first stream comprising the polyol and a second stream comprising the isocyanate, the first stream and the second stream being independent of each other. More preferably, the first stream comprises a mixture of the polyol and the organic wax. In this embodiment, the particulate plant nutrient can be contacted simultaneously with the first stream and the second stream. Alternatively, the particulate plant nutrient with the first stream followed by a second stream. In a further preferred embodiment, steps (a) and (b) of the present process are repeated at least once, to produce a controlled release fertilizer material having a plurality of coating layers.

In the following, embodiments of the present invention will be illustrated with reference to the following examples, which should not be used to limit or interpret the invention.

Example 1

In this example, a controlled release fertilizer material was prepared according to the teachings of US Pat. 5,538,531 [Hudson et al., (Hudson)]. Accordingly, it will be recognized that this example is provided for comparative purposes only and is outside the scope of the present invention.

The device used in this example was able to apply the coating components to a batch of 7.5 kg. The device consisted of a horizontal Plexiglas drum of 40.6 cm (16 inches) in diameter and 50.8 cm (20

45 inches) in length. The end plates of the drum had a central hole of 12.7 cm (5 inches) through which the components of the coating and the substrate are added. The internal elements of the drum consisted of four longitudinal baffles substantially evenly spaced, each baffle being approximately 2.54 cm (1 inch) tall. The drum was rotated at a peripheral speed of 9.38 m / s (75 fpm) or at approximately 18 rpm using a horizontal drum roller with a Separ ™ speed variator. The internal temperature of the drum and substrate was maintained at approximately 75 ° C using electric hot air guns and variable adjustment. The hot air guns were placed to direct the hot air through the holes in the end plates of the drum.

The coating components were added at a substantially consistent rate using pumps

55 individual peristaltic Masterflex ™ and a modified autosampler from Amacoil ™ Machinery. The sampler portion was removed and an individual stainless steel pipe for each component was attached to the speed variator. This allowed the coating components to be distributed along the entire length of the drum at a substantially constant speed.

The substrate used in this example was granulated urea (46-0-0). This substrate had a guide size number (SGN) of 240. The substrate (7.5 kg) was preheated in an oven at approximately 75 ° C and allowed to rotate in the coating drum until the coating temperature will stabilize at 75 ° C.

The polyol used in this example was commercially available castor oil in an amount of 42.95 g. He

The isocyanate used in this example was polymeric diphenylmethane diisocyanate (PAPI No. 17 of BASF) in an amount of 19.52 g. The two components were added simultaneously to the coating device, through individual pipes or pipettes near the top of the rotating bed. The coating of 2.5 percent by weight was applied to the substrate in three substantially equal layers, leaving approximately six minutes between the application of each layer, that is, the total weight of the coating was 2.5 percent by weight, based in the weight of the substrate.

image5

5 A commercially available C30 + alpha olefin wax from Chevron was preheated to approximately 150 ° C and then applied in a single layer to the urethane coated substrate. The wax was used in an amount to provide a weight of 1.5 percent by weight, based on the weight of the substrate. Six minutes after applying the wax, the drum and contents were cooled with a controlled stream of pressurized air at approximately 35 ° C.

Therefore, in this example, the sum of the urethane layer and the wax layer was 4 percent by weight, based on the weight of the substrate.

Next, the water release rate profile for the fertilizer release material was determined

15 controlled. In the analysis, a Technicon AutoAnalyzer ™ was calibrated and used according to the teachings of Automated Determination of Urea and Ammoniacal Nitrogen (University of Missouri, 1980). The following procedure was used:

one.

Accurately measure 15 grams (± 0.1 mg) of the sample on a weighing plate. Record the weight of the sample. Transfer the sample to a 125 ml Erlenmeyer flask.

2.

Add 75 ml of demineralized water and cover the flask.

3.

Shake the sample and water gently until all the particles are submerged.

Four.

Let the sample stand for a specific time at a constant temperature (typically at room temperature).

5. Gently shake the flask to mix the solution and decant only the solution into a 100 ml volumetric flask.

6.

Rinse the sample with demineralized water by adding it to the volumetric flask.

7.

Make up to the volume of the volumetric flask and mix thoroughly.

8.

If the test is to be repeated for another period of time, it must be repeated starting with Stage 2.

9.

Once the Technicon AutoAnaIyzer II is online, transfer some of the solution (or, if necessary, make the required dilutions) to the Technicon sample cups for analysis.

10.

Record the results in parts per million N-NH3 (read directly from a Shimadzu integrator).

Example 2

The methodology of Example 1 was repeated with the exception that, prior to the application of the urethane-forming polyol and isocyanate, the substrate was previously coated with the C30 + alpha olefin wax (preheated to approximately 150 ° C) applied as a single cap a. The wax was used in an amount to provide a weight of 0.3 percent by weight, based on the weight of the substrate. Accordingly, it will be recognized that this example is provided for comparative purposes only and is outside the scope of the present invention.

A three layer polyurethane coating was applied to the previously coated substrate as described in Example 1 (44.0 g castor oil and 18.4 g isocyanate). Again, the total weight of the polyurethane layer was 2.5 percent by weight, based on the weight of the substrate. A 600 g portion of the coated substrate was removed.

45 urethane.

Then, a three layer coating of C30 + alpha olefin wax (preheated to approximately 150 ° C) was applied to the rest of the urethane coated substrate. The wax was used in an amount to provide a weight of 1.5 percent by weight, based on the weight of the substrate (in this case, it was approximately 35 g per layer of the three layer coating).

Next, the water release rate profile for the controlled release fertilizer material was determined, using the test procedure described above in Example 1.

55 Example 3

In this example, a controlled release fertilizer according to the present invention was prepared.

The device used to apply the coating components was an isolated horizontal SS drum that had a diameter of 30.5 cm (12 inches) and a length of 14 cm (5 ½ inches). An integrated back plate was attached to a speed variator. The front plate had a central hole of 20.3 cm (8 inches) through which the components of the coating and the substrate were added. The internal elements of the drum consisted of four baffles substantially evenly spaced, each baffle being approximately 1.25 cm (½ inch) tall. The drum was spun at a peripheral speed of 0.38 m / s (75 fpm) or at

65 approximately 24 rpm. The internal temperature of the drum and substrate was maintained at approximately 75 ° C using a variable temperature electric hot air gun. The coating components were added using individual automatic macro pipettes, capable of adding ⅓ of the weight of each coating component in a single addition.

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The same substrate (1 kg) was used as in Examples 1 and 2, preheated to 75 ° C in the device (smaller)

5 described above. Castor oil (5.63 g) was mixed at 140 ° C with C 30+ alpha olefin (0.33 g). A coating was applied to the substrate consisting of three layers of 5.96 g (5.5% by weight of alpha olefin C30 + in castor oil) of the castor oil / wax mixture and 2.35 g of isocyanate added simultaneously to obtain a total coating weight of 2.5%. The period of time between the application of the successive urethane layers was approximately 6 minutes. The product was cooled six minutes after applying the final urethane layer.

10 Next, the water release rate profile for the controlled release fertilizer material was determined using the test procedure described above in Example 1.

The water release rate profiles for the controlled release fertilizer material produced in Examples 1-3 are illustrated in the attached figure.

As shown, when it is desired to have a material with a nitrogen release profile that extends for 6-8 months, the water release rate profile of the material produced in Example 3 (the invention) is significantly better than the of the material produced in Example 1 (the material according to Hudson). Likewise,

This was achieved using significantly less coating in Example 3 (2.5 percent by weight, based on the weight of the substrate) compared to Example 1 (4.0 percent by weight, based on the weight of the substrate).

With respect to Example 2 (precoating and subsequent wax coating), although the water release rate profile is closer to that achieved in Example 3 (the invention), this was achieved using a

The three-step procedure, while the material of Example 3 was prepared using a one-step procedure.

Consequently, the material of Example 3 and its production represent a significant advance over the prior art.

Claims (13)

image 1 1. A controlled release fertilizer material comprising a particulate plant nutrient surrounded by a coating, which is the reaction product of a mixture comprising: a polyol consisting of castor oil, an isocyanate and an organic wax, characterized in that: (i) the organic wax comprises a C20 + alpha olefin, and (ii) the coating is present in an amount in the range of about 1 to 4 percent by weight, based on the weight of the particulate plant nutrient, and the amount of organic wax in the mixture is in the range of 1 to 25 percent by weight, based on the combined weight of the organic wax and the polyol. 2. The controlled release fertilizer material according to claim 1, wherein the plant nutrient comprises a water-soluble compound selected from the group consisting of nitrogen, phosphorus, potassium, sulfur and mixtures thereof.

The controlled release fertilizer material according to claim 1, wherein the plant nutrient comprises urea.

Four.

The controlled release fertilizer material according to any one of claims 1 to 3, wherein the polyol comprises from about 2 to about 6 hydroxyl moieties.

5.

The controlled release fertilizer material according to any one of claims 1 to 4, wherein the isocyanate is selected from the group consisting of diphenylmethane diisocyanate, toluene diisocyanate, aliphatic isocyanates, their derivatives, their polymers and mixtures thereof.

The controlled release fertilizer material according to any one of claims 1 to 5, wherein the organic wax comprises a C30 + alpha olefin.

7.

The controlled release fertilizer material according to any one of claims 1 to 5, wherein the organic wax comprises a C20-40 alpha olefin.

8.

The controlled release fertilizer material according to any one of claims 1 to 7, wherein the coating is present in an amount in the range of about 2.0 to about 4.0 weight percent, based on the weight of the nutrient material for plants

35 9. A process for producing a controlled release fertilizer material, comprising the steps of:

(a) contacting a particulate plant nutrient with a mixture comprising: a polyol consisting of castor oil, an isocyanate and an organic wax to produce a coating surrounding the particulate plant nutrient, and (b) cure the coating to produce the controlled release fertilizer material, characterized in that: (i) the organic wax comprises a C20 + alpha olefin, and (ii) the coating is present in an amount in the range of about 1 to 4 percent by weight, based on the weight of the particulate plant nutrient, and the amount of organic wax in the mixture is in the range of 1 to 25 percent by weight, based on the combined weight of the organic wax and the polyol. Four. Five

10.

The method according to claim 9, wherein Step (a) comprises contacting the particulate plant nutrient with a first stream comprising the polyol and a second stream comprising the isocyanate, the first stream and the second stream being independent between yes.

eleven.

The process according to claim 10, wherein the first stream comprises a mixture of the polyol and the organic wax.

12.

The method according to claim 10, wherein Step (a) comprises contacting the nutrient

for plants particulate simultaneously with the first stream and the second stream. 55

13.

The method according to claim 10, wherein Step (a) comprises contacting the particulate plant nutrient with the first stream followed by the second stream.

14.

The process according to claim 10, wherein steps (a) and (b) are repeated at least once, to produce a controlled release fertilizer material with a plurality of coating layers.

fifteen.

The process according to any one of claims 9 to 14, wherein the organic wax comprises a C30 + alpha olefin.

The method according to any one of claims 9 to 14, wherein the organic wax comprises a C20-40 alpha olefin. 8 image2 17. The process according to any one of claims 9 to 16, wherein the mixture is used in an amount to produce a coating in an amount in the range of about 2.0 to about 4.0 weight percent, based on the weight of the nutrient material for plants. 9